The present invention relates to a method of preventing forgery of the record of patterns, such as characters, designs, etc., formed on the basis of the position, arrangement or configuration of regions in which diffraction gratings or interference fringe patterns are formed. The present invention also relates to a forgery-proof diffraction grating pattern or interference fringe pattern recording structure.
It has heretofore been known through calendars, bar codes, etc. to record and display patterns, such as characters, designs, etc., on the basis of the profiles of regions where diffraction gratings or interference fringe patterns are formed. Hereinafter, such a pattern will be referred to as "diffraction grating pattern".
It is also known that forgery-proof information is formed on cards or the like by using such a diffraction grating pattern.
In general, such a diffraction grating pattern can be readily read by a visual observation, and it is not always difficult to read and forge it.